Power-transmission device



Oct. 14, 1930. s. G. WINGQUIST 1,778,136

POWER TRANSMI SS ION DEVICE Filed Feb. 1, 1926 5 Sheets-Sheet 1 lill lllll llll' 1mm llllll I! IHI I! IN IHIIIIIII By Attorneys, amocn,?h a1m JWQQFLUZQ Oct. 14, 1930.

S. G. WINGQUIST POWER TRANSMISSION DEVICE '5 Sheets-Sheet 2 Filed Feb. 1, 1926 INVENTOR @W LWM By Attorneys,

Oct. 14, 1930.

S. G. WINGQUIST POWER TRANSMISSION DEVICE Filed Feb. 1, 1926 5 Sheets-Sheet 3 By ltorneys, 61 X W Oct. 14, 1930. s. e. WINGQUIST 1,778,136

POWER TRANSMISS ION I DEVICE Filed Feb. 1/ 1926 s Sheets-Sheet 4 INVENTOR @yww I By Attorneys, @W "W 21% Oct. 14, 1930. s. G. WINGQUIST 1,778,136

POWER TRANSMISSION DEVICE Filed Feb. 1, 1926 5 Sheets-Sheet 5 95% g 2* H; Egg? J 10mg 7 7L & I

INVENTOR By Attorneys,

I Patented Oct-l4, 1930 SVEN GUS'IAF WINGQUIST, OF GOTTENBOBQ, SWEDEN POWER-TRANSMISSION DEVICE Application filed February 1, 1926. Serial No. 85,291.

This invention relates to improvements in poweptransmitting devices of the type particularly applicable to automobile drives and permitting variable speed transmission from the internal combustion engine to the propeller shaft of the vehicle. I

' One object of the invention is to provide a transmission device having great flexibility and yet being relatively simple in construction, whereby its cost is materially reduced, the normal direct drive and speed reductions being had through a hydraulic transmission,

but, at the same time, additional emergency speed reductions for exceptional conditions in load being provided by combining the hydraulic transmission with mechanical gearlng also mgearing. The mechanical cludes a reverse gear.

A further object of the invention is to providev a clutch brake of novel construction,

which is automatically thrown into operation whenever the gear shift of the mechanical transmission is set.in neutral position. The invention further contemplates the combination of a hydraulic transmission device with. a hydraulic braking system, the

braking energy being supplied by a moving part of the transmission system instead of by the operator of the vehicle.

The invention also provides improved means for maintaining reserve-fluid in communication with the hydraulic transmission and at a definite hydrostatic pressure, whereby the action of the transmission is rendered -more positive and regular.

Certain structural improvements are also provided in hydraulic power transmission devices which render the automatic speed or transmission ratio control of such devices more positive, and further improvements resulting in a substantially'perfect balance'of fluid pressure acting on the major parts of the fluid-pumping systems, whereby on'e sided thrusts on the transmission bearings are practically eliminated. Further objects of the invention will be pointed out in connection with the following detailed description, reference being had to the accompanying drawings'in which:

Figure 1 is a side elevation of the assemtransmission which is adapted to be carried Within the engine fiy-wheel shown in Fig. 1, and also shows details of the hydraulic pump-braking device.

Fig. 3 is a vertical cross-section through the delivery pump of the hydraulic transmission, taken along the line III- 111, Fig. 2.

Fig. 4 is a vertical cross-section taken through the receiving pump along the line IV-JV as shown in Fig. 2.

Fig. 5 is a vertical cross-section taken through the automatic valve control mechanism situated to the right of the transmission pumps in Fig. 2, the section being taken along the lineV-V. I

.Fig. 6 shows the same View as Fig. 5, except that the valve control pistons and the pilot valve are shown in different positions.

Fig. 7 shows the main valve control pistons in Fig. 2 position, the view being taken along the same section as that chosen-in Figs.

5 and 6.

Fig. 8 is a vertical section transverse to the transmission axis, taken along the line VIIIVIII in Fig. 2, showing the details of the hydraulic clutch brake and vehicle braking device.

Fig. 8 shows the rotary abutment in the open position. v

Figs. 9 and 10 illustrate in enlarged detail, and respectively in plan and side elevation, the automatic control of the clutch brake as it is connected to the mechanical transmission gear-shift mechanism.

For the purpose of describing the present invention it will beunnecessary to enter into detailed description of the hydraulic transmission illustrated, as such transmission, except for minor structural differences, is fully described in my United States Letters Pat-- ent No. 1,603,179, granted October 12, 1926. The hydraulictransmission, details of which are illustrated in Figs. 2, 3 and 4, is of the type-known as the differential pumping transmission. The engine power is applied I seenin Figs. 3 and 4, these elements are both provided with a number of vanes 5, which slide in slots cut in the internal pump ele-- ments 3 and 4. The housing 2, common to both the internal pump elements 3' and 4, is provided with working surfaces 6 and abutments 7 adapted to coo 'erate with the driven -y transmitted to the driven element. It will rotor and the stator to orm two separate and distinct pump devices.

The pump formed between the driven rotor 3 and thecommon housing 2 will hereinafter be referred to as the delivery pump or pump A, as indicated in Fig. 2, and the pump formed between the stator 4 and the common housing 2 will be referred to as the receiving pump and will be generally referred to by the letter B. It will be understood that the term receiving pump applies to a form of pump which receives fluid under pressure and which in its operation adds to the torque applied to the driven elements of the transmission, such pump therefore possessing the function of a motor. 1

Communication may beestablished between the two pumps A and B so that, if the external housing 2 be rotated by the engine around the driven rotor 3, fluid will be forced from the pump A into the receiving pump B. This fluid underpressure entering the pressure chambers of the pump B will exert a thrust against the vanes 5 of such pump; but the element 4 being under certain conditions immovable, there will be a fluid reaction against the abutments 7 carried by the-housing 2, which fluid reaction is.favorable to the rotation of the housing and acts to materially increase the torque on such housing, such increased torque being transferred to the driven rotor 3 through increased fluid-pressure acting upon the vanes thereof.

Communication between the delivery pump A, and receiving pump B is hadthrough the pressure channel 10, in the right-hand end of which a rotary sleeve valve 11 is mounted.

vThis valve is adapted to control'the flow of fluid from the delivery pump tothe receiving pump. In one position the valve will prevent any escape of fluid from the delivery pump. As is well understood, if under such circumstances power is applied to the rotor or housing 2, the internal rotor 3 cooperating with such housing to form the delivery pump will be driven without any slip whatever, the fluid locked between the cooperating vanes and abutments of such pump providing a. substantially rigid connection between the driving'and driven elements.

In'another position the valve 11 vents the 55 ,fluid acted upon by the delivery-pump into casing 13 surrounding the pumps. If the and within the oil-retaining shell or port of the valve providing this venting of the delivery pump be opened wide, there will be practically no delivery of power through the transmission, the drivingpart rotating freely about the driven rotor 3 because, while fluid isbeing delivered by the pump A formed between the housingand the, driven rotor, no resistance is ofiered to the flow of this fluid, and consequently no torque. will be Y fluid delivered by the pump A will meet with greater and greater resistance to flow,'with a consequent building up of fluid pressure,

;which will result in a driving force being gradually applied to the driven rotor 3.

When the valve 11 is adjusted to open the vent to the idle fluid or suction chamber 12 of the transmission, the transmission is adjusted to a condition pf .free engine. As the vent is gradually restricted by'themovement of the valve, a gradual clutching action will be brought about. The valve then upon a further movement opens the communication between the pressure chamber of the delivery pump and the receiving pump. At such time the transmission is adjusted for a hydraulic speed reduction, the speed ratio between the driving and driven rotors beingdetermined by the relative volumetric capacity of the delivery pump and-the receiving pump.

If the capacity of the delivery pump per revolution is very large compared with the capacity of the receiving pump per revolution, a comparatively slight relative move' ment-between the driving and driven elements of the delivery-pump will result in the delivery of oil sufficient to fill the cham= bers of the receiving pump, and this condition obviously corresponds to a slight gear reduction, that is to say, thedriven rotor lags behind the driving rotor only slightly.

If, on the other hand, the capacity of the receiving pump were made somewhat larger in comparison with that of the capacity of the delivery pump, a greater slip would occur between the drlvmg and driven elements inorder that the delivery pump could deliver suflicient fluid to meet the volumetric requirement per revolution of the receiving pump, and this obviously would occasion a greater speed reduction in the transmission.

The automatic mechanism for controlling the position of the main valve 11 in accordance with the conditions of load and engine speed and other features herein referred to are described and claimed in my copending United. States applications, Serial Nos.

575,673, applied for July 17, 1922; and.

91,758 appliedv for March 2, 1926, and in'my United States Patents Nos. 1,610,405, granted .December 14, 1926; 1,610,406, granted December 14, 1926; 1,645,565 granted October general consideration-of the operation of the power transmission device according to the present invention, the valve control mechanism is at all times sensitive to the combined v 23 of the vehicle.

and opposing actions of centrifugal force and fluid pressure, the fluid pressure being .an index of the torque load, and the centrifugal force an index of the speed of the motor.

A valve so constructed and properly adjusted actually controls the operation of the slipping clutch and hydraulic change speed gear in much the'same way that the clutch and change speed gear in the usual vehicle would be manipulated by an expert driver.

As shown in Fig. 1, the hydraulic clutch and change speed gear G, which takes the place of the usual engine flywheel, is combined with a mechanical gear transmission of usual type. The mechanical transmission is provided with a direct drivecoupling between a toothedelement 20, which is rigidly connected to the driven shaft 19 of the hydraulic transmission, and an internallytoothed member 21, which is slidably splined to a shaft 22 connected to the propeller shaft When the internal and external toothed elements 20 and 21 are shifted into engagement by actuating the selector-rod 25 by means of the usual gearshift'lever' 26, the mechanical transmission is set for direct drive.

The mechanical transmission is also provided with a single speed reduction and one reverse speed. The forward gear reduction is obtained by shifting the gear 28, which is slidably splinedon the shaft 22 connected to the propeller shaft of the vehicle, into engagementwith the gear 29 which is mounted on the jack-shaft or counter-shaft 30. The

- jack-shaft is driven in the usual manner by a gear 31, which is permanently meshed with a driving gear 32 rigidly mounted on the shaft delivering power to the mechanical transmission. As is well understood, when the transmission lever 26 has been shifted from neutral position into the position corresponding to a reduced speed, the power is not transmitted directly from the shaft which carries gear 32, to the shaft 22, but is first delivered to the jack-shaft 30 through the gear 31 and is then delivered through gears 29 and 28 to the driven shaft 22.

When it is desired to reverse the drive, the gear-shift lever 26 is brought. into engagement with the actuating notch 34 of the selector-rod 35 controlling the shifting fork 36, which fork, according to the usual prac-- tice, engages a thrust collar 37 formed on one face of the gear 28. The lever 26 is then I movedinto the position for reverse. In such position the selector-rod acting on the shifting fork will have moved the gear 28 into engagement with the reverse gear 38. The reverse drive, according to the usual ractice, is constructed as shown, a relatively small pinion 38 being mounted for free rotation on a stud 39, the pinion 38 permanently meshing witha gear 40 rigidly mounted on the jack-shaft 30. As is apparent, the pinion 38 will rotate in a direction opposite to that of the rotation of the jack-shaft As in the case with all mechanical gear shifts for use in automobiles, a clutch brake is required. The clutch brake, according to usual practice, takes the form of a simple friction pad which engages the releasable part of the clutch and accordingly. brings such part to rest, so that if the transmission be set in neutral position, and the car is standing still, the low speed gear 28, for example, which will also be stationary because with the gear 29 on thejack shaft because of the action of the clutch brake above referred to, which, if permitted to operate for a relatively brief interval of time, will bring the driven element of the clutch, when it has been released, to a state of rest. With the engine rotating there will always be a certain drag on thedriven element of the clutch, even though the clutch be released to the greatest possible extent, and this drag will be ample'to cause the driven element of the clutch to take up the speed of the engine and cause the gears within the mechanical transmission, which, when the transmission is set in neutral, are entirely free to r0 tate, to'spin at substantially the same speed as if they were directly connected to the engine. If an attempt is made to mesh either of the gears on the shaft 22 with one ofthe gears thus rotated by the engine, very unpleasant sounds will be produced, and with considerable likelihood of serious injury to the gears.

Heretofore the clutch brake has been brought into operation by a movement of the clutch pedal of the car to its extreme forward position, thus insuring that the releasable element of the clutch has been disconnected from the driving element before the clutch brake is applied to such releasable driven element. This clutch braking action normally occurs every time the clutch pedal is depressed by the operator. It is well understood that the clutch pedal is very frequently depressed when the operator is not required to shift gears or has no intention of shifting gears, and this results in excessive wear of the clutch-braking means, much of which is entirely unnecessary. According to the present invention this difliculty is overcome in two ways. In place of the usual friction pad device which is utilized to check the rotation of the driven element of the clutch, a hydraulic pump is operatively connected to the said driven shaft. This pump, when not set to act as a brake, normally circulates fluid from its pressure chambers to its idle fluid or receiving chambers without requiring practically any energy whatever to rotate it. When, however, a brakingaction is required, the flow of fluid between the pressurea'nd suction chambers of this pump is restricted, thus building up a pressure which resists the rotation of the driven pump element. It will be seen that a type of clutch brake is now provided which is possessed of exceptional durability. Since the fluid medium upon which the pump operates is one possessing suitable lubricating properties, the pump will show practically no wear over long periods of use, and so would remain operative even if subjected to exceptional duty. But in addition to this improved clutch braking device the invention provides a novel means for automatically throwing it intooperation. The automatic control of the hydraulic pump brake is effected through a mechanical connection between the gear shifting mechanism and an element'in the pump which controls the circul'ation of 'fluid. The device is shown in sition immediately under the brake-control lever 52, andthis lever will drop into such notches, thereby 'causing a rotation of the shaft 53 which results in the application of the clutch brake. This active position of the clutch brake actuating lever is shown in Figs.

1 and 10; If after the clutch brake has reduced the speed of the driven element of the clutch totha't required for quiet engagement of the desired gears, and the gear shift le ver 26 bemoved to couple such gears together. the actuation of either one of the gear selector rods 25 .or 35 will cause one or the other of the cam notches 50 or 51 to elevate the brake control lever 52 to the position shown in Fig. '10, in which positionthe' clutch brake is thrown out of operation.

From the foregoing description it will be apparent that the clutch brake is never operative when the gears are in driving connectlon, and is automatically thrown into operation" when the mechanical gear shiftis -in neutral position, at which time only the speed of the gears connected tothe free element of the clutch should be controlled Details of the fluid pump braking device are shown in Fig. 8. It may be here pointed out that the same'braking device which is automatically controlled by the gear shift lever 26 to provide a clutch braking action when the gear shift is set in neutral position, is-also adaptable to other uses requiring the delivery of fluid under pressure. very important use of this pump is illustrated in Fig. 8, and will now be described.

Rigidly fastened to the shaft 19 which receives power from the engine, is an internal rotor 61 carrying vanes 62 which co-operate preferably with a stationary external housing 63 in which are mounted abutments 64 to provide a rotary vane pump. The onlyrespect in which this pump diflers from pumps A and B previously. described, and which type of vane pump is well known in the art, is that instead of fixed abutments as those illustrated, for example, at 7 in Fig. 3, the abutments 64 of the brake pump are rotatable. The two abutments, as shown, are cylindrical and adapted for free rotation within bores 65 in the main casting constituting the externalv housing 63. As shown, the upper and lower portions of the housing. casting are-extended to provide-a suitable mounting for the abutments' and' fluid connections and control means therefor required by the pump and its various appurtenant devices. j

It will be apparentthat if the abutments 64 be rotated into-the position indicated by the dotted lines in Fig. 8 (see Fig. 8) an entirely unobstructed communication will be established between the pressure chamber 66 and suction or idle fluid chamber 67 of the rotary vane pump; With the-abutments in this position practically no effort whatever will be required to rotate the internal rotor 61 of the pump, and consequently no braking action will take place.

The automatic control of the abutments 64 previously referred to in connection with the automatic ciutch braking function, at no time ever need rotate the abutment to the fully active position indicated insolid lines in Fig. 8, as in such position the abutment provides practically a fluid lock, the fluid being trapped in .the pressure chamber and not permitted to escape, except at excessive pressures,

which escape is permitted through a relief valve 68 which will be more particularly de scribed hereinafter. The braking action arising from a complete closing of the abutment would be far too violent for the uses of a clutch brake. The great pressures which can 'be built up, however, within the pump by fully closing the abutment, are, however, .utilized to advantage in producing a braking action on the vehicle itself. This is brought about in two ways,

In the first place, if the shaft 19 be rotated 4 either by the engine orby, the .inovement of the car in coasting down a hill, for example, a

i about theshaft .19. 500pounds acting, on apumping action as described above will be set up by the movement of the vanes 62 toward the abutments. If the abutments are adjusted to'completely close communication between the pressure and suction chambers of the 7 pump, and the tension on the relief valve 68 be anymoment equal to the product of the exposed area,of such vanes and the fluid pres sure. If thetotal area of the opposed active vanes, for example, is five square inches, and

the relief valve is set to give rise to a pressure of 100 pounds to the square inch, a braking forceof 500 pounds will be exerted on an arm, let us say, six inches long, this latter figure representing the mean radiusof'the exposed, pressure area of the vanes rotating six-inch arm will produce a braking torque of 250 pounds-feet, which torque acts directly upon an element'of'the-vehicle drive producing its braking effect uponthe wheels of the car through the differential and rear axles.

In addition to. the direct braking action upon the shaft 19, the brake pump is utilized in still another way to further increase the braking effect upon the motion of the vehicle itself. It will be borne in mind that while the brake pump is provided with two abutments and consequently has two pressure chambers and two suction chambers 66 and 67 respectively, that the two like chambers on opposite sides of the pump are always in open 'communication one with the other through conduits 70 and 71, the conduit 70 being a pressure conduit and 71 the suction or idle fluid conduit. Thereforeit will be understood that any fluid-controlled meansconnected to either the pressure or suction chambers 66 a'nd67 atthe top ofthe pump will also be in effective communication with the corresponding pressure I and suction chambers at the lower part of the pump, so that fluid delivered from both pressure chambers will act upon any control devices connected directly to the upper pressure chamber.

pumping action that is effected when the abutments 64 are rotated to the closedposition and the internal rotor 61 is set in mo .tion. Bearingin' mind the fact that the rotation of the pump can be caused to set up any desired fluid pressure having a maximum The operation of the relief valve 68 has already been explained, as well as the value, in accordance with the regulation of the relief valve 68, it will be readily understood that a source of fluid pressure is hereby available for actuating hydraulic brakes, as they are now peculiarly termed in the art, such brakes comprising one or another of the usual frictional braking devices acting upon the brake drums of the car, or a similar device connected to the propeller shaft of the serve fluid container 80. By this means any fluid which may leak past the brake control piston 75 will be caught and returned to the reserve fluid system. Furthermore, the construction described provides a practically airtight working chamber for the pistons'75, which protects the pistons and cylinders from the action of moisture or wear due to foreign particles being picked up on the working surfaces, as would necessarily be the case if the pistons were operating in open-ended cylinders. It will be seen that the suction chambers of the pump are at all times also in direct communication with the reserve fluid container 80 through the conduit 81, by which means the pump is always insured of an adequate supply of oil if the oil level in the container 80 is maintained,

.and, furthermore, by keeping the pump completely filled with oil (or whatever the fluid medium employed for transmission purposes may be), any air that wouldv otherwise be present in the pump, and which would tend to become mixed with the transmission fluid, will be expelled and pass out through the vent 82 in the fluid reserve tank.

For the purpose of effectively varying the pressure of fluid acting upon the brake pis= tons 75, the shaft which controls the abutment 64 is connected to an adjusting device under the control of the operator. Furthermore, the two'abutments 64 shown at the upper and lower portions of the pump housing are operatively connected together by means of a bent connecting rod 91 upon either end of which is formed a rack 92, which-racks engage pinions 93, the latter being rigidly fastened to the abutment shafts 90 projecting through the pump housing. The pinions 93 are shown in Fig. 1 and Fig. 8. I

The control mechanism which may be actuated by the operator of the vehicle to adually restrict the communication between the pressure and suction chambers of the pump,

and consequently gradually build up a fluid pressure within'the transmission which may be utilized directly to resist the rotation of one of the inoving parts of the car, such as the shaft 19, or to apply frictional brakes under the hydraulic control of the pistons '75, may be constructed in the following manner:

Acontrol pedal95 may be conveniently positioned in 'front of the driver in accordance with the usual arrangement of the brake or clutch pedal. The pedal 95 controls a bellcrank arm 96 suitably pivoted on a shaft 97.

The lower arm of the bell-crank 96 is loosely pinned to a rod 98 at the right-hand end of which an inclined cam surface 99 is formed. The end of the rod 91, which rod, as before described, carries the racks 92 for actuating the abutment pinions, is slotted to receive the mitted the rack bar to return to its normal.

position in which the abutments are fully open. The return of'the rack vbar to such normal position is eflectedtbya compression spring 100 acting against the lower extremity of the rack bar 91. The brake'pedal 95 may be restored to its normal inoperative position by any' suitable means such as a coiled spring 101 fastened tothe shaft on which the brake pedal is pivoted-1 The brake control, above described obviously providesall degrees of pump abutment adjustment from wide open to thefully closed position, so thatthe degree of braking, up to the maximum pressure limit atwhich the relief valve .68 is set, will be determined by the position of the brake pedal 95. Aglight pres-' sure on such pedal, causing it to move only a slight distance toward the floor,-will produce only a slight restriction, of the passage between the pressure and suction chambers of the pump, and consequently only a slight braking action, and a further movement will increase the braking action up to any desired point. A valve 105 is with the hydraulic brake-actuating pistons. This valve may be closed when it is desired to utilize only the direct braking action of the pump upon the shaft 19 vdue to the resistance offered to the fluid flow by the closure of the abutment 64. When the brake-is utiprovided in the vcon duit T7 connecting the pressure chamber of the pump lized in this manner, when considerable braking duty is required, considerable pressure will be developed in the pressure chamber up to that at which the relief valve 68 lifts off its seat, and thereafter a constant braking effort will be exerted upon the shaft 19 through the circulation of oil from the delivery pump through the relief valve chamber and abypass conduit 106 which communicates directly with the suction chamber of the pump on the opposite side of the abutment.

Ordinarilythe valve 105 is left open, so that both the direct drag of the pump on the shaft 60 and the hydraulic braking action" of the pistons 7 5, will be utilized simultaneously. The control of the brake pump abutment 65 by the brake pedal is rendered independent of the automatic control of such abutments for clutch-braking purposes through a lost motion connection 110 between 'shaft53 and the hub projection 111 of the shaft 99 of the upper abutment 64. This connection' is a simple one-way drive comprising a collar mounted on'shaft 53, which collar is provided with a driving finger 112 which projects beyond the end of shaft 53 and normally engages a driving pin 113 projecting radially from the hub projection 111. If the brake pedal is released and under-the influence of' spring is returned to its normal inopera- .tive position, and the automatic clutch brake actuating lever 52 is in inoperative position, a the finger 112 will be in contact with the pin 113 of thelost motion drive. If the gear shift be now set in neutral. position, the clutch transmission, and it is desired to actuate the vehicle brake, pressure on the brake pedal 95 will, as hereinbefore described, result in a downward movement .of the rack bar 91, and a corresponding rotation of the pumpabutments,1?the abutments being entirely free to move in a direction to apply the brakes, because of the fact that the lost motion connection between the abutment hub projection 111 and the shaft 53 is a one-way drive; that is to say. the pin 113 on the abutment hub projection is free to rotateaway from' the driving finger -112 and quite independentlythereof.

It will'be observed. that the reserve fluid receptacle 80, inaddition tothe connections previously described, is connected to the interior of the hydraulic transmission housing through a conduit 115 comprising a bore 116 in the housing 124 of the stationary stator checking device 125 and the fluid brake pump. The bore 116 communicates with an idle fluid fluid chamber 12 of the transmission, which chamber is common to both of the pumps A and B of the transmission and also the compartment 120 occupied by the automatic transmission ratio control mechanism; By this means there is provided at all times a connection between the reserve fluid receptacle80 and the interior of the rotating housing of the hydraulic transmission, and consequently the transmission will always be maintained entirely full of the fluid transmission medium so long as the reserve fiuidreceptacle is kept atleast partially full.

This reserve fluid receptacle is preferably mounted at a certain elevation above the hydraulic transmission so that the fluid within the transmission will be kept under a slight hydrostatiepressure,which pressure insures the completeiilling of the pumps at every vane intake and also insures the expulsion of air from the transmission proper, which feature is important. If any appreciable amount of air is trapped within the transmission, apart from the fact that excessive pressures might be 'developed,which, if they did not injure the transmission, would certainly tend to cause excessive leakage at all bearing points exposed to the fluid pressure, such air would 7 mix with the transmission fluid, rendering it seml-elastic instead of practlcally incompressible, as it should be. The action of the transmission illustrated upon an elastic or semielastic fluid is not entirely satisfactory, and for this reason the elimination of all air from the transmission is desirable.

For a full explanationof the principle of operation of the automatic valve control thereby housed within a member taking the mechanism shown Fig. 5, reference may be had to the inventors co-pending United States applications previously referred to. Certain details of construction will be herein pointed outwhich render such control particularly. applicable to the present transmission primarily because these details relate to aconstruction by whichthe space occupied by the automatic valve control may be materially reduced and the entire hydraulic transmission place of the ordinary engine fly wheel and occupying no greater space than the usual fly wheel, thus rendering the transmission adaptable to existing automobiles, the whole device being readily inserted between the engine and the propeller shaft of the present auto? mobiles. Two complete valve control devices areillust'rated inFig. 5, one tothe right, and

1 one to the left of the driven shaft 19. Only one of these devices will be described, it being borne in mind that the two are in every respect identical. The control is duplicatedfor two driven directly by the engine. Within this housing to the right of the pumps A and B and in a separate compartment 120 are mounted the two valve control devices, one of which will now be described. A rackbar 130 is slidably mountedon the transmission casting in such manner that its two racks 131 and 132 will respectively engage the pinions'133 controlling the main valves 11. The two main valves 11 are shown in section in Fig. 4, but both do not appear in Fig. 2 for the reason that the section line is not taken along the diameter of the transmission but along two different radii, as indicated by line IIII in Fig. 3. The rack bar takes the form of an L, the lower arm 134 of which is designed to have considerable mass. This mass being disposed at a considerable distance from the axis of rotation of the housing will be subjected to a relatively large centrifugal force when the housing is rotated, and this force will at all times be governed by the speed of-rotation of the housing. In close proximity to the rack bar 130, a cylinder 135 is provided, the cylinder being divided by transverse partitions- 136 and 137 into three pressure chambers 138,

139 and 140 respectively. The lower end of v the cylinder is closed by a head 141,

municates with the pressure chambers 139' and 138 respectively so that when fluid is admitted to the pressure chamber it will act upon the piston 146 in such chamber and will also flow through the bore of the piston rod and act upon the piston ,in pressure chamber 139. The 'fluid will also enter through the described bore and port 150 the pressure chamber 138, where it will act upon a compound piston comprisinganinnerplunger and a relatively slidable sleeve piston 161 of annular cross-section. The said sleeve piston freely'slides within the cylinder 135 but is provided with piston rings or other suitable packing means for rendering its contact with the cylinder walls substantially fluid-tight. The plunger 160, freely slidable within thesaid sleeve piston, also is efl'ectively sealed therein, so that no fluid will pass between the plunger and the sleeve piston.

T he sleeve piston 161 acts against a shoulder 162 on the plunger in such manner that so long as the said sleeve piston is not in contact with the end of the cylinder 135, its thrust will be added to the thrust of the plunger.

According to the arrangement described, the

plunger will, however, continue beyond such point in its outward movement without the assistance of the thrust of the sleeve piston 161. Substantially the same explanation 'is applicable to the action of pistons 145 and 146. These two pistons only exert a thrust upon the plunger 160 while they are in the position illustrated in Fig. 6 and while moving to that shown in Fig. 5. When they reach theposition shown in Fig. 5, they are checked against further upward movement by coming in contact with the partitions 136 I and 137 respectively, and beyond this point also cannot exert any thrust upon the plunger 160 through the operative connection, otherwise afforded by the piston rod 147. The upper end of-such piston rod is adapted to engage the end of the plunger 160 when such plunger is in any position lower than that indicated in Fig. 5. Thus, when the plunger 160 is in the position shown in Fig. 6, it will be subjected to the combined fiuid pressure acting upon the three pistons 146, 145 and 161, and by the fluid pressure acting directly upon its own effective pressure area. By the above described construction, it will be apparent that thereis provided in a cylinder of limited bore, such as the cylinder 135, a

. compound piston arrangement, which, in the position in which all the pistons are active,

the combined'clfective pressure area of the. device is three times that which would be afforded by a similar valve control which had only a single piston. After the upward 'movement of the three pistons 145, 146 and 161 has been stopped, as described, the

plunger 160, if its relatively smalleffective pressure area be subjected to a sufficiently augmented fluid pressure, will continue to move outward to a position indicated in dotted linesv (Fig. 5). Thus the valve control piston device has two distinct positions of rest, one determined by the point at which certain of the pistons are checked in their upward or outwardmovement, andanother, in which after the movement 'oftthe plunger 160 is continued without the aid of the thrust a. bore in the weighted end 134 of the rack bar. The forces of the spring and the fluid creasing torque actuated plun er are at all times opposed to the centri ugal force acting upon the weighted end 134 of the rack bar. Centrifugal force always acts on the rack bar in a direction tending to rotate the transmission control valve to a position corresponding to direct drive, whereas the fluid pressure acting upon the combined piston device through plunger "160 tends opposite direction and establish a reduced transmission ratio, and in extreme-cases to carry the control valve to a' point at which it permits the slipping clutch action in the delivery pump to take place. If the speed of the engine remain constant, at say 1000 R. P. M., and the torque load be increased, if the transmission control valve is set in the position corresponding to direct drive, the following. action'will take place: The inload will produce an increased fluid pressure within the transmission. This fluid pressure will be communicated to the control cylinder 135, and upon reaching an intensity suflicient to overcome the centrifugal force acting on the weight 134. will shift the rack bar to the position indicated in Fig. 5, the pressure during this movement acting upon all four pistons 146, 145, 160 and 161 to produce the necessary thrust. reduced gear ratio, which, if the load be not too great, will be suflicient to enable the This will set the transmission in a to move the valve in the engine rotating at 1000 R. P.'M. to continue to carry the load. If, however, the load be of such magnitude thateven in a reduced vtransmission speed the engine is overloaded to a point that would otherwise compel it to slow down, there will be sufiicient fluid pressure within the cylinder to move the plunger to the position shown in dotted lines in Fig. 5, such pressure acting at this time solely upon the effective pressure'area of the plunger itself. A movement of the plunger from the position shown in Fig. 5' in full lines to that shown in Fig. 5 in dotted lines will permit the hydraulic slipping clutch action to gradually increase. Thls slipping clutch action will prevent the engine. from slowing down and permit it to run at a speed some- .where in the neighborhood of the speed at. -which the engine develops its maxlmum torque.

' Now let us suppose that the engine throttle is opened wider and the engine gradually increases its speed. The increase in engine speed will-result in an increased centrifugal force acting. upon the weight 134, which. when it attains a certain degree, will be sufficient to overcome thevfluid pressure acting upon the effective pressure area of the plunger alone, and such centrifugal force will move the plunger into the position shown in full lines in Fig. 5, which position corresponds to the normal'hydraulic gear reduction of the transmission in reduced speed. A further increase in engine speed a will result in the development of suflicient centrifugal force acting .upon the'wei ht 134 to overcome the combined pressures c all the pistons and carry them to the position shown in Fig. 6, which position corresponds to direct drive. i

The communication between the cylinder 135 in which the valve control pistons are located, and the ressure chamber of the delivery pump of t e transmission (pump A), is re ulated by an auxiliary or pilot valve D 1n a casing 180 which valve is fully described in my aforesaid United States Patent No. 1,67 3,542, granted June 12, 1928, to which reference should be made for a complete disclosure thereof.

While only a sin 1e embodiment of the invention has been ereinbefore particularly described and illustrated, it is to be underembodiment but may be otherwise variously embodied and modified without departing from the spirit of the invention,- as set forth in the following claims.

. What'Iclaim i I 1. A power transmission device comprising a hydraulic clutch and change speed mechanism, a mechanical change speed gear, clutch-braking means adaptedto resist the rotation of the driven art of. said hydraulic mechanism, a gear shi ing element, and an operative connection between said element and said braking means whereby the latter will be automatically caused to act asa clutch brake to resist the motion of the said driven part when the saidgear shiftingelement is moved toward neutral position.

2. A-powertransmission device comprising a hydraulic transmission and a mechanical change speed gear, theformer having a driving and a driven part, said driven partbeing releasable for free rotation whereby to unclptch the power from the drivingparts of said change speed gear, frictional means adapt-ed to bring the drivin parts of the said gear to a with the speed of the driven-parts of said gear whereby to permit the-engagement of the said. drlving and driven arts of the change speed gear without shoe gear shiftr, ing mechanism, and an operative .connectlon between said mechanism and said frlctional ,of the'change speed relationship for smoo means whereby when the said an shiftin mechanism is opera'tedthe sald frictions means will bring the driving and driven part8 giver into proper speed t engagement. i 3.- A. transmission device according claim 2, said frictional means hung a fluid pump having means for the flow 4. A transmission device according to rotational spee commensurate abutment and a relatively rotary part having vanes, the means for controlling flow through said pump comprising a movable part adapted in one position to serve as such abutment and in another position to permit free flow between the chambers ofthe pump. 5. A power transmission device comprising a mechanical change speed gear, a clutch, a clutch brake, a gear-shifting means, and an operative connection between said means and said clutch brake whereby the clutch brake will be automatically applied when the said shifting means of the mechanical gear is set in the neutral position, the said clutch brake bein a fluid pump 0 eratively connected to the riven element 0 the clutch and having means for restricting the flow of fluidwhereby to resist the rotation of the said driven element. "6. A power transmission-device comprising a mechanical change speed gear a clutch,

, through said, pump comprising a movable p'art adapted in one position to serve as such abutment and in another position to permit free flow between, opposite chambers of the pump, and a connection between said movable part and the-gxear shift lever adapted to interpose it as suc flow when said lever is in neutral positionabutment to restrict the and displace it to open such free flow as the lever is moved from neutral position.

7. In a vehicle, a power transmission device ccm rising a mechanial change speed ar, a c utch through which such gear is riven, a hydraulicpump a plied between said clutch and change spee gear, adapted to; retard the releasable member of said clutch, and hydraulic brake actuating means for the vehicle, said means receiving fluid pressure from said pump.

In witness whereof, I have hereunto signed ngy name.

V'EN GUSTAF WINGQUIST.

a rotary fluid pump 00111191181118; casing 

